G1358
(Revised February 2007)
Feeding to Maximize Milk Protein
and Fat Yields
Rick Grant, President, Miner Agricultural Research Institute
Paul J. Kononoff, Extension Dairy Specialist
This NebGuide describes feeding guidelines to
increase milk fat and protein production.
Proper feeding management of dairy herds can both
improve the economy of production and provide a healthier
cow. To achieve these goals, producers must feed to increase
production of milk with maximum levels of milk fat and
protein.
Milk solids components include fat, protein, lactose and
minerals. Normal values for milk fat typically range from 3.7
percent (Holstein) to 4.9 percent (Jersey); milk protein ranges
from +3.1 percent (Holstein) to 3.8 percent (Jersey). Lactose is
usually 4.6–4.8 percent for all breeds; minerals (ash) average
.74 percent. Because current milk pricing formulas emphasize
milk fat and protein, maintaining milk fat and protein tests
provides an economic advantage. Normal milk fat percentages also reflect good rumen and cow health. Generally, diets
which cause low milk fat test also cause sore feet (laminitis),
acidosis and feed intake problems. Milk protein has economic
value because higher protein leads to higher cheese yields.
Consequently, milk protein content of milk is emphasized.
How Can Milk Solids be Altered?
Factors which affect milk composition include genetics,
stage of lactation, level of milk production and age of cow,
environment, disease (i.e. mastitis) and nutrition. Of the variation in milk composition, 55 percent is due to heredity and
45 percent is due to environmental factors, such as feeding
management.
If the milk protein to milk fat ratio is less than .80 for
Holsteins, milk protein depression is a problem. When this
ratio is greater than 1.0, the herd suffers from milk fat depression (low milk fat test). Milk protein percent follows changes
in milk fat test, except during milk fat depression and when
high levels of fat are fed. The following feeding guidelines
should help the dairy producer increase production of both
fat and protein in milk.
Feeding Strategies to Maximize Milk Solids
The following guidelines are critical to maximizing
solids-corrected milk production:
1. proper ration formulation;
2. maximum feed intake;
3. monitoring dietary composition (use routine forage, feed
analyses);
4. harvesting and/or buying high-quality forage and proper
forage allocation;
5. properly feeding protein, energy, fiber, minerals and
vitamins.
Because ration changes can be made rapidly, they are
most effective in responding to changing market demands.
Important aspects of feeding management to produce high
levels of milk solids are outlined below.
Maximize Feed Intake
The importance of maximizing feed intake is related to
minimizing negative energy balance during early lactation.
As cows move into positive energy balance, body weight is
regained, losses in body condition score are recovered and
cows produce milk of normal fat and protein composition.
Increased feed intake can improve milk protein by .2–.3 units.
This increased milk protein percentage may be due to overall
increases in balanced energy intake as total feed intake increases. High-producing dairy cows should eat 3.6–4.0 percent
of their body weight or more daily as dry matter.
Example:
1,350 pound cow x .04 (4 percent)
= 54 pounds of dry matter intake
If the diet is 50 percent dry matter, the cow should eat
108 pounds as fed (54/50 = 108). If a herd is consuming less
dry matter than 3.5–4.0 percent of bodyweight, production of
solids-corrected milk may be limited. Major feeding factors
which affect feed intake include:
1. feedbunk management (keeping them clean, shaded during hot weather and adequate space-per-cow);
2. feeding frequency and sequence;
3. ration moisture (50 percent moisture or less);
4. social interactions (“boss” cow problems when heifers
and mature cows are mixed together in one group);
5. sudden ration changes;
6. proper flooring, bedding or ventilation.
Increased feeding frequency may increase fat test, especially with diets which are low-fiber and high in grain. The
greatest response is seen in diets with less than 45 percent
forage or when grain is fed separately, as in parlor feeding.
When diets are fed as total mixed rations, feeding frequency
is not as important, as long as feed remains palatable, fed at
least once daily, and frequently used up.
Properly Feed Concentrates
Properly feeding concentrates involves maintaining proper
forage-to-concentrate ratios and non-fiber carbohydrate (NFC)
levels. NFCs include starch, sugars and pectin. NFC content
is calculated as:
NFC = 100 – (crude protein + neutral detergent fiber + fat + minerals)
Non-fiber carbohydrates should range between 30–40
percent. A level of 40–45 percent is typical of diets with forage-to-concentrate ratios of 40 to 60 or less forage. Diets with
large amounts of high-quality forage and minimal grain may
be NFC-deficient. While feeding the proper amount of NFC,
producers can only improve both milk fat and protein test,
overfeeding of NFC leads to milk fat depression of one unit
or more and may increase amounts of milk protein percent
by .2–.3 per unit.
The amount of grain-per-feeding should be limited to
seven pounds to avoid rumen acidosis, off-feed problems and
reduced fat content. The following grain feeding guidelines
will maximize milk fat and protein production:
Holstein and Brown Swiss
Milk Level (pounds) less than 40 41 to 70 greater than 70 the effectiveness of a fiber source for stimulating rumination (cud chewing), salivation and maintaining normal milk
fat and protein composition. Minimum acid detergent fiber
(ADF) levels required in the ration dry matter are 19–21
percent. Neutral detergent fiber (NDF) should not fall below
26–28 percent. Below these levels, cows risk a low milk fat
test, acidosis, lameness, chronic feed intake fluctuations and
poor body condition, especially in early lactation. To assure
adequate particle length, do not chop forage to less than 3/8
inch theoretical length of cut (TLC). In addition, no more than
10 percent of the Total Mixed Ration (TMR) should be >0.75”.
More information concerning ration particle size is given in
NebGuide G1587, Understanding Effective Fiber in Rations
for Dairy Cattle. Finer chopping may dramatically decrease
fat percent and increase milk protein percent by .2–.3 units.
As with overfeeding non-fiber carbohydrates (starchy concentrates), even though milk protein content increases, neither
the cow, nor her rumen, are healthy. Feeding inadequate fiber
is not recommended for increasing milk protein content. Of
the neutral detergent fiber in typical diets, 75 percent should
come from long or coarsely-chopped forage.
Rations too high in fiber may limit energy intake which,
in turn, may limit milk protein production. Generally, 40–50
percent forage dry matter is the minimum amount to avoid
low milk fat test. When feeding 65 percent or more forage,
it must be high in quality, to avoid the energy deficiencies
which lower milk protein. For different corn silage and alfalfa
haylage mixtures (dry basis), the following minimum forage
dry matter levels are recommended:
Forage Mixture Grain Level
1 pound per 4 pounds milk
1 pound per 3 pounds milk
1 pound per 2.5 pounds milk
Percent of dry matter from forage
100 percent corn silage 75 percent corn silage:
50 to 60 percent
25 percent haylage 50 percent corn silage:
45 to 55 percent
Breeds with High Milk Solids
Milk Level (pounds)
Grain Level
less than 30 1 pound per 3 pounds milk
31 to 60 1 pound per 2.5 pounds milk
greater than 60 1 pound per 2 pounds milk
50 percent haylage 25 percent corn silage:
45 to 50 percent
75 percent haylage 40 to 50 percent
100 percent alfalfa haylage 40 to 45 percent
Grain should be limited to a maximum of 30–35 pounds
per cow daily. Manure containing much undigested corn or
with a pH less than 6.0 indicates too much grain, or non-fiber
carbohydrates, is being fed.
Grain processing also can influence milk composition.
For example, flaked corn may increase milk protein percentage, while oats have decreased milk protein percent by .2
unit compared with barley. Generally, rolled or ground barley
or flaked corn, when overfed, will cause a rapid and severe
decrease in milk fat. Fibrous byproducts, such as soybean
hulls, can replace starchy grains and reduce the severity of
milk fat depression. University of Nebraska–Lincoln research
indicates soybean hulls can replace 50–75 percent of the corn
in a concentrate mix to maintain normal milk fat test.
Feed Adequate Protein
Meet Fiber Requirements
Fiber requirements of dairy cattle include both fiber
concentration and fiber particle size, which contribute to
Meeting the dairy cow’s protein requirements — both
crude and escape — is essential to maintaining normal milk
protein test. For a 1,300-pound cow producing 4 percent milk
fat, crude protein requirements range from 15 percent for 50
pounds of milk to 18 percent for cows producing 110 pounds
of milk. For cows in early lactation (90 to 120 days in milk),
the amount of escape protein should range from 33–40 percent.
Although a precise requirement has not been defined, it appears
having at least 33 percent rumen undegradable protein (as a
percent of crude protein) is necessary to maintain normal milk
protein levels. Overfeeding crude protein may also result in
excessive nitrogen excretion and environmental pollution.
Generally, dietary crude protein concentration affects
milk yield, but not milk protein percentage, unless the diet is
Table I. Summary of feeding management changes which alter milk solids production.
Management Factor Milk fat percent Milk protein percent
Maximum intake Increased feeding frequency of grain Underfeeding energy little effect High NFC¹
(> 45 percent) Normal NFC (30-40 percent)
Excessively high fiber Low fiber²
(< 26 percent NDF) Small particle length³ High crude protein Low crude protein Escape protein
(33–40 percent of CP) Added fat
(> 7–8 percent) increase increase .2–.3 units decrease increase .2–.3 units
may increase slightly
.1–.4 units
decrease by 1 percent or more increase marginal increase increase .1–.2 units
maintain normal level
decrease .1–.4 units
decrease by 1 percent or more decrease by 1 percent or more no effect
no effect increase .2–.3 units
increase .2–.3 units
increase if previous diet was deficient
decrease if diet is deficient
no effect increase if previous diet was deficient
variable decrease by .1–.2 units
¹NFC = nonfiber carbohydrates
²Low dietary fiber, high non-fiber carbohydrates, small forage particle length and low forage levels all may increase milk protein percent and greatly reduce milk
fat test. These are not desirable ways to improve milk solids-not-fat. These feeding practices cause acidosis, lameness, and feed intake fluctuations. The cow is
not healthy.
³Less than 15 percent of particles greater than 2 inches indicates inadequate particle length.
deficient in crude protein. For example, a producer may feed
his herd a 14.5 percent crude protein ration when the requirement is 16.5 percent. This herd will probably have a low milk
protein test, which often occurs when poor-quality forage is
fed and the producer has not tested the forage to properly
formulate a grain mix. Also, feeding excessive degradable
crude protein, such as urea, can reduce milk protein. Generally, limit urea feeding to cows past 120 days in milk. Urea
should make up only 1–2 percent of the concentrate mix to
maintain palatability and it works best when mixed well into
the diet as with a total mixed ration.
Niacin, fed at 6–12 grams per day, may correct the milk
protein depression seen with high levels of fat feeding. Also,
limit fat feeding to the first 120 days in milk, balance the
ration for non-fiber carbohydrates and crude protein, follow
recommended limits for fat sources, feed proper forage levels
and increase calcium and magnesium concentrations to .95
percent and .35 percent of ration dry matter. Higher levels
of these two minerals counteract their loss as calcium and
magnesium soaps when higher levels of fats are fed.
Summary
Feeding practices proven to maximize solids-corrected
milk production include:
Added Fat and Milk Protein
Supplemental fat feeding is increasingly common as
production levels per cow surpass 20,000 pounds/year. It is
necessary to follow guidelines when feeding fat, to avoid
a drop in milk protein level of .1–.2 unit. If fed properly,
added fat results in maintained or slightly increased milk fat
percentage, relatively little change in milk protein test and
increased milk production. The net result: total production
of milk protein and solids-not-fat increase.
Generally recommended guidelines for fat feeding are:
Source Maximum Percent of Ration Dry Matter
Forages, grains (basal diet)
Natural fats
whole oil seeds
tallow
Protected fats
3 percent
2 to 4 percent
1 pound
1 pound
2 percent (1 pound)
Total 7 to 8 percent maximum
1. maintaining a proper fiber level of 26–32 percent neutral
detergent fiber of adequate particle length;
2. maintaining a proper starch level with 40–45 percent
NFC maximum;
3. keeping forage to concentrate ratio in line with forage
sources;
4. maintaining a proper crude protein of 16–18 percent;
5. maintaining a proper escape protein of 33–40 percent of
crude protein;
6. staying within recommended guidelines for fat feeding;
7. maximizing intake of a balanced diet.
Table I summarizes feeding practices which influence
milk solids. Correctly feeding dairy cows is the only way to
produce milk with maximum levels of milk fat and protein.
UNL Extension publications are available online
at http://extension.unl.edu/publications.
Index: Dairy
Feeding & Nutrition
1998, Revised February 2007
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